Lawrence I. Silverman, who heads a real estate firm that has sold 40,000 houses over the past 25 years, refuses to be unhinged by the current slowdown in the market.

"I have a strong feeling that mortgage rates will come down from the currently frustrating level of over 14 percent," Silverman said, "but not before early spring. I also think the buying public will accept rates around 13 percent."

But the head of Lewis & Silverman Realtors also senses that the long-term, fixed-rate mortgage may be fading away as competition for money widens.

He sees as inevitable the use of variable- and renegotiated-rate mortgages -- along with those in which the lender has an equity position (in exchange for below-market rates). I just hope that the fixed-rate FHA and VA mortgages will survive as alternatives."

But the market for housing in the next decade should be "phenomenal," Silverman maintains. "The demand is there, pent up now by mortgage rates and the economy. And the desire for and confidence in homeownership is higher than ever. We don't have to sell the concept anymore. It's just a matter of affordability."

Silverman also predicts that more unrelated buyers will be looking for two-bedroom, two-bath houses to share.

The 1950s were the years of the single house; the 1960s were the time when town houses became the popular update of the familiar rowhouse, and the 1970s saw the emergence of the condominimum, Silverman noted.

"The market during the next decade will be wide open, and will include dwellings that combine one-story apartments and two-story town houses," the broker said. "Condo apartments and units built one over another on a small scale are the starter homes today."

The sales company has represented more than 400 subdivisions since it was started 30 years ago by Irvin Lewis, and currently has about 60 builders as clients. Silverman joined it in 1955 and started out by selling 35 houses in the Four Corners area.

Lewis & Silverman went on to become strong in the sales of subdivision houses and Lewis made Silverman a partner. Lewis sold his interest to Silverman 12 years ago and is in commercial real estate sales with Ivor Clark Co. here. The former partners are still good friends.

In the past decade Lewis & Silverman also turned to the marketing of resale houses. It plans to open a branch in the Spring Valley area of Northwest -- its ninth -- early next year.

"Although our aim is not to be the biggest, we likely will have 20 offices by 1985," Silverman said. "Roger Drebeen, who's now a junior partner and executive vice president, has been responsible for a lot of our growth." Silverman says that, over the years, his company has become expert in telling builders what to build, advising on the kind of house that will sell in a certain location and what kind of lots to buy."

Silverman's beliefs about the best locations changed in the 1970s. Now he regards adjacency to the Beltway and the Metro system as prime. He urges builders to avoid remote locations "that are not near anything."